Use of Ultra-High-Performance Concrete for Bridge Deck Overlays

Research Project

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Use of Ultra-High-Performance Concrete for Bridge Deck Overlays

Researcher(s)

Principal investigators: Sri Sritharan, 515-294-5238, sri@iastate.edu (project list)
CCEE, Iowa State University

Project status

Completed

Start date: 05/01/16
End date: 03/31/18

Publications

Report: March 2018, Use of Ultra-High-Performance Concrete for Bridge Deck Overlays 7.25 mb (*pdf)

Related publications: Use of Ultra-High-Performance Concrete for Bridge Deck Overlays 975.30 kb *pdf March 2018

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Sponsor(s)/partner(s)

Sponsor(s): Federal Highway Administration
Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation

About the research

Abstract:

A large number of bridges in the nation are rated as structurally deficient and require immediate retrofits or replacements that will impose a significant financial burden on bridge owners. A fast, cost-efficient, and reliable retrofit solution is needed to tackle this problem. Typical bridge deck deterioration starts with shrinkage cracks, and additional cracks may occur due to traffic loads and time-dependent effects, which are worsened by freeze-thaw cycles over time. These cracks then lead to water and chloride penetration into the concrete deck, causing rebar corrosion and further damage to the superstructure.

A potential solution, suggested in a previous study, is to apply a thin layer of ultra-high-performance concrete (UHPC) on top of normal concrete (NC) bridge decks. Because UHPC has a higher tensile strength and low permeability, cracking as well as water and chloride ingression can be minimized, which in turn will extend the lifespan of the bridge. Moreover, UHPC is also deemed to have a higher fatigue resistance than NC.

In this study, a new UHPC mix to accommodate surface crowning was developed by a material supplier and tested in the laboratory. Using this new mix, the thin UHPC overlay concept was successfully implemented on a county bridge in Iowa. The implementation involved state and county engineers, a local contractor, and a material supplier. The bridge overlay was periodically monitored, and thus far there have been no concerns regarding the performance of the UHPC overlay or the bond at the interface between the UHPC and NC layers. In addition to the field implementation, three concrete slabs with and without a UHPC overlay were tested in the laboratory.

The results showed that a UHPC overlay in the positive moment region increased the strength by 18% while showing a more ductile response. In the negative moment region, although wire mesh was used, its effectiveness was not significant due to its small steel area. The effectiveness of the wire mesh could be improved by increasing the amount of steel area within the overlay, but its impact on the UHPC-NC interface bond needs to be evaluated.

2711 S. Loop Drive, Suite 4700, Ames, Iowa 50010-8664
Phone: 515-294-9501 ~ Fax: 515-294-0467
The Bridge Engineering Center is administered by Iowa State University's Institute for Transportation.

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